Adjustable support for arc chamber of ion source

ABSTRACT

An assembly present in an ion source for supporting an arc chamber upon a base plate includes a first arc support plate, a first screw, and a second screw. The first screw passes through a smooth through-hole in an arm of the first arc support plate and extends into a bore in the base plate. The second (or adjustable) screw passes through a threaded through-hole in an arm of the first arc support plate and engages an upper surface of the base plate itself, and can be used to change the altitude and angle of the first arc support plate relative to the base plate. This adjustment ability improves the beam quality of the ion source.

PRIORITY CLAIM AND CROSS-REFERENCE

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 63/175,301, filed on Apr. 15, 2021, which is incorporated byreference in its entirety.

BACKGROUND

Ion implantation is a process used in the manufacturing of semiconductordevices. Implantation of various atoms into a silicon crystal latticemodifies the conductivity of the lattice in the implanted location,permitting the manufacture of the various parts of a transistor. An ionimplanter generally includes an ion source, a beam line, and a processchamber. The ion source produces ions. The beam line organizes the ionsinto a beam having high purity in terms of ion mass, energy, andspecies. The ion beam is then used to irradiate a substrate in theprocess chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a schematic diagram of an ion implanter, with which the ionsources of the present disclosure can be used in accordance with someembodiments.

FIG. 2 is a schematic diagram of an ion source in accordance with someembodiments.

FIG. 3A is a schematic diagram illustrating an arc chamber which has anexit slit that is aligned with the slit of the extraction electrode, inaccordance with some embodiments.

FIG. 3B is a schematic diagram illustrating an arc chamber which has anexit slit that is not aligned with the slit of the extraction electrode.

FIG. 4 is a front view of a first embodiment of a first arc supportplate, in accordance with some embodiments.

FIG. 5 is a top view of the first arc support plate of FIG. 4.

FIG. 6 is a side view of the first arc support plate of FIG. 4.

FIG. 7 is a perspective view of the first arc support plate of FIG. 4.

FIG. 8 is a front view of a first embodiment of a second arc supportplate, in accordance with some embodiments.

FIG. 9 is a top view of the second arc support plate of FIG. 8.

FIG. 10 is a side view of the second arc support plate of FIG. 8.

FIG. 11 is a perspective view of the second arc support plate of FIG. 8.

FIG. 12 is a perspective view of a base plate, in accordance with someembodiments.

FIG. 13 is a perspective view that illustrates the engagement of an arcsupport plate with the base plate, in accordance with some embodiments.

FIG. 14 is an exploded view illustrating the relative locations ofvarious components of the ion source, in accordance with someembodiments.

FIG. 15 is a perspective view of a second embodiment of a first arcsupport plate, in accordance with some embodiments.

FIG. 16 is a perspective view of a second embodiment of a second arcsupport plate, in accordance with some embodiments.

FIG. 17 is a perspective view of a second embodiment of a base, inaccordance with some embodiments.

FIG. 18 is a perspective view of a third embodiment of a first arcsupport plate, in accordance with some embodiments.

FIG. 19 is a perspective view of a third embodiment of a second arcsupport plate, in accordance with some embodiments.

FIG. 20 is a perspective view of a third embodiment of a base, inaccordance with some embodiments.

FIG. 21 is a flowchart illustrating a method for adjusting an angle ofan arc chamber, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Numerical values in the specification and claims of this applicationshould be understood to include numerical values which are the same whenreduced to the same number of significant figures and numerical valueswhich differ from the stated value by less than the experimental errorof conventional measurement technique of the type described in thepresent application to determine the value. All ranges disclosed hereinare inclusive of the recited endpoint.

FIG. 1 is a schematic diagram of an ion implanter (not drawn to scale)100, which is generally performed in a vacuum environment. The ionimplanter system includes a new ion source 110 according to variousembodiments of the present disclosure. The ion source includes an arcchamber 120. One end of the arc chamber includes a cathode 122 with ametal filament 124 located therein, and an anode 126 is present at theopposite end of the arc chamber. The cathode and the filament may bemade of any suitable materials, for example a refractory metal or alloy.In particular embodiments, such materials can include niobium,molybdenum, tantalum, tungsten, rhenium, and alloys and combinationsthereof. In particular embodiments, the cathode and the filamentcomprise tungsten.

The metal filament is coupled to a first power supply 130 capable ofsupplying a high current. When heated by the current, the metal filamentreleases electrons. The cathode emits secondary electrons when theelectrons from the filament hit the cathode. A source magnet 132 createsa magnetic field inside the arc chamber to confine the electrons. A gassource 134 supplies a dopant gas (e.g., BF₃ or AsH₃ or GeF₄ or PH₃) tothe arc chamber. A high voltage is then applied across the cathode andthe anode to produce a plasma. A biased extraction electrode 140 canthen extract ions from the plasma through an exit aperture/slit 128 ofthe arc chamber. A repeller 136 at the other end of the arc chamberopposite the extraction electrode may be biased to repel the ions andsend them through the exit slit. The extraction electrode itselfincludes a slit 142 through which the ion beam 150 passes.

The resulting ion beam 150 enters the beamline 160. The ion beam firstpasses through a mass analyzer where the beam is focused and bentthrough an angle, which can range for example from 70° to 90° .Electromagnetic fields can be used to change the radius of the bend andthus select the ion species that will exit the mass analyzer based ontheir mass to charge (m/e) ratio. Only the desired ions having theselected m/e ratio will exit the mass analyzer. Lighter ions will hitthe inner wall of the bend, while heavier ions will hit the outer wallof the bend. A movable aperture or electromagnetic lens can be used tolocate the exit in the appropriate location for the desired ions. Inthis way, only the desired ions are selected from the different ionsthat may originate from the ion source. The beam of selected ions isthen accelerated to the desired energy. Other elements, such as lenses,electrodes, and filters may also be present in the beam line to producethe final desired ion beam 155. The ion beam 155 is then steered usingelectromagnetic fields to strike a region of a substrate 170, so theseions can be implanted into the substrate as dopants at desiredlocations/depths. The substrate can be, for example, a wafer made ofsilicon, germanium arsenide (GaAs), or gallium nitride (GaN). Inparticular embodiments, ion implantation methods described in thepresent disclosure use silicon wafers as the substrate.

These dopants can enable the device or structure to have desiredproperties, which are essential for various applications. For example,source and drain regions of a semiconductor device are formed usingdopants that have a different polarity from the substrate, and allow thesemiconductor device to be turned on and off with a gate voltage. Thesource and drain regions can be formed by implanting ions in desiredlocations on the substrate.

Continuing, FIG. 2 is a schematic diagram showing the ion source 110 ofthe present disclosure, in accordance with some embodiments. As seenhere, the arc chamber 120 and the extraction electrode 140 areseparately attached to a base plate 175. The extraction electrode 140 ismounted upon an adjustable support arm (not visible) which is affixed tothe base plate 175. The arc chamber 120 is mounted to a first arcsupport plate 180 and a second arc support plate 190. The base plate 175contains two recesses, one on each side, which is engaged by an arcsupport plate. Arms 182, 192 on each arc support plate rest upon theupper surface 176 of the base plate. Other portions of the ion sourceare located below the base plate, such as those components that providethe dopant gas. It should again be noted that the ion source can beoriented in any direction, such as vertical or horizontal.

Systems incorporating the ion sources of the present disclosure operateadvantageously as illustrated in FIG. 3A. As described further herein,the exit slit 128 of the arc chamber 120 is more easily aligned with theslit 142 of the extraction electrode, so that the ions of the ion beamenter the beamline instead of being deflected (by the extractionelectrode or other components).

The ion sources and components of the present disclosure can avoidproblems that occur when, over time, due to high temperature exposure,the upper surface can warp. This can occur, for example, due todeficiencies in the design of the cooling system, which typically do notfocus on the base plate itself. As seen in FIG. 3B, this warpage of thebase plate can cause the arc chamber 120 (and more specifically, theexit slit 128) to lose alignment with the slit 142 of the extractionelectrode 140. As a result, the ion beam 150 does not travel straight inthe desired direction, resulting in lower beam quality due to loweramounts of the desired ions being provided by the ion source. Thisaffects further downstream activities. For example, referring back toFIG. 1, the ion beam must be aimed at the desired location of asubstrate for a longer time period to obtain the desired dose of dopant.This additional time decreases the overall throughput of the ionimplanter.

The ion sources and systems of the present disclosure include, invarious embodiments, arc support plates for supporting the arc chamberwhich permit adjustment of both the altitude and the angle of the arcchamber (rather than fixing the arc chamber in a given position). Insome embodiments, the arc support plate includes at least one arm (andin further embodiments, two arms on opposite sides) that extend forwardpast a front face of the arc support plate. Each arm contains aplurality of through-holes, with at least one of the through-holes beinglocated beyond the front face of the arc support plate. In particularembodiments, one through-hole is smooth (i.e. does not contain athread), and is aligned with a threaded bore in the base plate. Athreaded screw passing through this smooth through-hole is used to fixthe arc support plate to the base plate. Another through-hole is alignedwith the upper surface of the base plate, and is threaded internally. Athreaded screw passing through this threaded through-hole engages thesurface, and can change the altitude and the angle of the arc supportplate (and the attached arc chamber) relative to the base plate.

FIGS. 4-7 are different views of a first embodiment of a first arcsupport plate 200, in accordance with some embodiments. FIG. 4 is afront view. FIG. 5 is a top view. FIG. 6 is a side view. FIG. 7 is aperspective view.

The first arc support plate 200 includes a main portion 210 having afront face 212 and a rear face 213. The main portion includes an upperend 214 and a lower end 216. Two arms 240 are present on opposite sidesof the main portion, with the front face being located between the twoarms. The arms can be considered as defining the upper end and the lowerend. Two shoulders 218, 220 are present near the arms, such that thelength 215 of the upper end is shorter than the length 217 of the lowerend. A leg 222 extends downwards from the lower end of the main portion,and is offset to one side. The main portion and the leg generally have auniform thickness 211 (in the direction of the x-axis). Six holes extendthrough the thickness of the main portion and through front face. Theseholes are used for engaging fasteners that attach various components(including the arc chamber) to the arc support plate. Two holes 231, 232are located at the upper end, two holes 233, 234 are located at thelower end, one hole 235 is located in the leg, and one hole 236 islocated in a central area of the main portion and vertically alignedwith the hole located in the leg.

Each arm 240 extends beyond the front face 212 in the direction of thex-axis, as best seen in FIG. 5 and FIG. 6. A plurality of through-holesis present in each arm 240. As illustrated here, three through-holes242, 244, 246 are shown in dashed lines. Through-hole 246 is threaded,while through-holes 242, 244 are smooth. In this embodiment, thethreaded through-hole 246 is also located in the portion of the armlocated beyond the front face. In particular embodiments, thethrough-holes have a diameter of 5 mm +/−1 mm.

As a result, two additional alignment holes (i.e. threaded through-holes246) and two additional adjustable (or alignment) screws (not shownhere) are added to the modified first arc support plate.

FIGS. 8-11 are different views of a first embodiment of a second arcsupport plate 300, in accordance with some embodiments. FIG. 8 is afront view. FIG. 9 is a top view. FIG. 10 is a side view. FIG. 11 is aperspective view.

Similarly, the second arc support plate 300 also includes a main portion310 having a front face 312 and a rear face 313. The main portion 310includes an upper end 314 and a lower end 316. Two arms 340 are presenton opposite sides of the central area of the main portion, with thefront face 312 being located between the two arms. The arms can beconsidered as defining the upper end and the lower end. Three holes 331,332, 333 extend through the front face along a longitudinal axisthereof, which are used for engaging fasteners that attach variouscomponents (including the arc chamber) to the arc support plate. Onehole 331 is located at the upper end, one hole is located at the lowerend 332, and one hole 333 is located in a central area of the mainportion. Unlike the modified first arc support plate illustrated inFIGS. 4-7, the modified second arc support plate does not includeshoulders or a leg.

Each arm extends beyond the front face in the direction of the x-axis,as best seen in FIG. 9 and FIG. 10. A plurality of through-holes ispresent in each arm. As illustrated here, three through-holes 342, 344,346 are shown in dashed lines. Through-hole 346 is threaded, whilethrough-holes 342, 344 are smooth. In this embodiment, the threadedthrough-hole 346 is also located in the portion of the arm locatedbeyond the front face. In particular embodiments, the through-holes havea diameter of 5 mm +/−1 mm.

As a result, two additional alignment holes (i.e. threaded through-holes346) and two additional adjustable (or alignment) screws (not shown) areadded to the modified second arc support plate.

It is noted that the first arc support plate 200 and the second arcsupport plate 300 have different shapes. This is because the first arcsupport plate also supports additional components for using the metalfilament as described in FIG. 1. Because the second arc support platedoes not need to support such components, it can be of relativelysmaller size. This will be seen further in FIG. 14, below.

FIG. 12 is a perspective view of the base plate 400 in accordance withsome embodiments of the present disclosure, which engages the first arcsupport plate 200 and the second arc support plate 300. The base platehas an upper surface 402, a lower surface 404 opposite the uppersurface, and two recesses 406, 408, one on each side of the base plate.The recesses extend entirely through the thickness of the base plate.The first arc support plate 200 will engage recess 406 with its lowerend, while the second arc support plate 300 will engage recess 408 withits lower end. Alignment pins 410 are present near each recess, each ofwhich may engage one of the smooth through-holes on an arm of an arcsupport plate. A bore 412 is also present near each alignment pin. Athreaded screw (not shown) will pass through one of the smooththrough-holes on each arm of an arc support plate and the tip of thethreaded screw will engage the bore, to fix the arc support plate inplace. The head of the threaded screw can contact the arm of the arcsupport plate. It is noted that the first arc support plate, second arcsupport plate, and base plate of FIGS. 4-12 are intended to be usedtogether as a first embodiment of an assembly for supporting an arcchamber.

FIG. 13 is a perspective view that illustrates the engagement of a firstarc support plate 200 with the base plate 400. A first threaded screw(or fixed screw) 450 passes through smooth through-hole 242 on each armof the arc support plate and the tip of the screw engages the bore 412,to fix the first arc support plate in place. The fixed screw 450 mayinclude a smooth shank near the head of the screw, or may be threadedalong the entire length of the shaft. A second threaded screw (oralignment screw) 460 will pass through the threaded through-hole 246 oneach arm of the arc support plate and the tip of the screw will pressagainst the upper surface 402 of the base plate. In some embodiments,the alignment screw 460 is threaded along the entire length of itsshaft. The altitude of the arc support plate can be adjusted upwards anddownwards by turning the alignment screw 460, due to engagement with thethreaded through-hole of the arm 420 and against the upper surface ofthe base plate 400. The smooth through-hole will travel along the lengthof the fixed screw. The altitude and/or angle of the arc support platerelative to the base plate can thus be adjusted by appropriateadjustment of the alignment screws on the two arms of the arc supportplate.

In particular embodiments, a first (i.e. fixed) screw and a second (i.e.alignment) screw are used with the arc support plates and assemblies ofthe present disclosure. In embodiments, the first screw and the secondscrew have different lengths. In more specific embodiments, the firstscrew and the second screw differ in length by at least 0.5 mm. Inparticular embodiments, the screws have a length of about 3 mm and about2.5 mm. Generally, the longer screw passes through the smooththrough-hole and into the bore in the base plate. In particularembodiments, the two screws are socket head cap screws. In otherembodiments, the heads of the screws may be knurled, so that the screwscan be adjusted by hand.

FIG. 14 is an exploded view of an assembly 470 illustrating the relativelocations of various components of the ion source. Here, the base plate400, the first arc support plate 200, the second arc support plate 300,arc chamber 120, and extraction electrode 140 are shown. An anode 126,cathode 122, and filament clamp 125 are also shown.

Initially, the base plate 400 includes a first side recess 406, a secondside recess 408, and a rear side recess 420. The extraction electrode140 is attached to an adjustable support arm 144 which passes throughthe rear side recess 420 and attached to the base plate. The first arcsupport plate 200 engages the first side recess 406. Alignment pins onthe base plate can engage through-holes in the arms 240 of the first arcsupport plate. A cathode support 123 is attached to two holes of thefirst arc support plate. Two angled filament clamps 125 are attached tothe other four holes of the first arc support plate. The second arcsupport plate 300 engages the second side recess 408. Alignment pins onthe base plate can also engage through-holes in the arms 340 of thesecond arc support plate. An anode support 127 is attached to the threeholes in the main portion of the second arc support plate. The arcchamber 120 is engaged by the cathode 122 and the anode 412, which inturn engage the cathode support 123 and the anode support 127,respectively. The lid 121 of the arc chamber includes an exit slit 128.

A total of four alignment screws are present in this assembly, two perarc support plate. These alignment screws can be used to adjust thealtitude and angle of the arc chamber 120 relative to the base plate 400and the extraction electrode 140, such that the ion beam passing throughthe exit slit 128 of the arc chamber lid also passes through the slit142 in the extraction electrode. The angle of the arc chamber can beadjusted along both the x-axis and the y-axis of the base plate.

FIGS. 15-17 are illustrations of a second embodiment of an arc chambersupport assembly, in accordance with some embodiments. FIG. 15 is aperspective view of a second embodiment of a first arc support plate200. FIG. 16 is a perspective view of a second embodiment of a secondarc support plate 300. FIG. 17 is a perspective view of a secondembodiment of a base plate 400.

Comparing FIG. 15 to FIG. 7, the first arc support plate of FIG. 15still includes arms 240 that extend beyond the front face 212. However,the arms only include two through-holes 242, 246. One through-hole 246is also located beyond the front face. One through-hole 246 is threaded,and one through-hole 242 is smooth.

Similarly, comparing FIG. 16 to FIG. 11, the second arc support plate ofFIG. 16 also includes arms 340 that extend beyond the front face 312.However, the arms only include two through-holes 342, 346. Onethrough-hole 346 is also located beyond the front face. One through-hole346 is threaded, and one through-hole 342 is smooth.

Finally, comparing the base plate of FIG. 17 to that of FIG. 12, thebase plate 400 does not include the alignment pins. The alignment pinstypically engage the third through-hole present in the embodiments ofFIG. 7 and FIG. 11, but can be removed if desired since they may not beengaged if the altitude adjustment (using the alignment screws) raisesthe arc support plate above the alignment pin. Otherwise, the assemblyof FIGS. 15-17 would operate in the same manner as described above withrespect to FIG. 13.

A third embodiment of an arc chamber support assembly is alsocontemplated. In the first and second embodiments illustrated in FIGS.4-12 and FIGS. 15-17, the alignment screws pass through the arms of thesupport plates and push against the base plate. In the third embodiment,the alignment screws pass through the base plate and push against thearms of the support plates. This third embodiment can be described asreversing the arrangement described in the embodiments of FIGS. 4-17.

In the third embodiment, the arc support plates include at least one arm(and in further embodiments, two arms on opposite sides) that extendforward past a front face of the arc support plate. However, the portionof the arm beyond the front face is solid, or in other words does notcontain a through-hole. Instead, the base plate now includes anadditional internally-threaded through-hole for each arm which extendsentirely through the base plate (i.e. from the lower surface to theupper surface). The alignment screw passes through this threadedthrough-hole and engages the surface provided by the portion of an armon a support plate, which can change the altitude and the angle of thearc support plate (and the attached arc chamber) relative to the baseplate.

FIGS. 18-20 are illustrations of this third embodiment of an arc chambersupport assembly 500, in accordance with some embodiments. FIG. 18 is aperspective view of a third embodiment of a first arc support plate 200.FIG. 19 is a perspective view of a third embodiment of a second arcsupport plate 300. FIG. 20 is a perspective view of a third embodimentof a base plate 400.

Comparing the first arc support plate of FIG. 18 to that of FIG. 7, theembodiment of FIG. 18 still includes arms 240 that extend beyond thefront face 212. However, the arms do not include through-holes in theportion extending beyond the front face. Instead, that portion of thearm provides a lower surface 248 which can be engaged by the alignmentscrew. The remaining portion of the arm can contain two through-holes(like FIG. 7) or one through-hole (like FIG. 15), depending on whetheralignment pin(s) are present on the base plate or not.

Similarly, comparing the first arc support plate of FIG. 19 to that ofFIG. 11, the embodiment of FIG. 19 also includes arms 340 that extendbeyond the front face 312. However, the arms do not includethrough-holes in the portion extending beyond the front face. Instead,that portion of the arm provides a lower surface 348 which can beengaged by the alignment screw. Again, the remaining portion of the armcan contain two through-holes or one through-hole, depending on whetheralignment pin(s) are present on the base plate or not.

Finally, comparing FIG. 20 to FIG. 12, the base plate 400 includes atotal of four additional through-holes 420, one for each of the two armson the two arc support plates. Each through-hole is internally threaded.Each through-hole is located so as to engage an arm of an arc supportplate. It is noted that these through-holes differ from the bores 412because the bore does not extend through the entire thickness of thebase plate, whereas the through-hole does extend through the entirethickness of the base plate. Alignment pins 410 may or may not bepresent in this third embodiment.

In use, it is contemplated that in this third embodiment of an assembly,each alignment screw 460 passes through a thread-hole 420. The head ofthe alignment screw 460 would contact the lower surface 404 of the baseplate, rather than contacting the arms of the arc support plates as inFIG. 13. The tips of the alignment screws would push against the arms ofthe arc support plates, rather than pushing against the base plate as inFIG. 13. This third embodiment might be useful in applications where itis desired to adjust the altitude and angle of the arc chamber from adifferent location.

The first arc support plates, second arc support plates, and base platesof the present disclosure can be made using known manufacturingprocesses. They may be made from suitable materials which can withstandhigh temperatures, such as refractory metals and alloys. Examples ofsome materials may include nickel, zirconium, stainless steel, titanium,chromium, niobium, molybdenum, tantalum, tungsten, and alloys thereof.They can be made in the desired shapes by casting, molding, and similarprocesses. Finishing processes may include drilling to provideholes/bores in desired locations, grinding, etc. They are then used inan ion source as an assembly for supporting an arc chamber, andadjusting its angle and altitude to improve beam quality.

FIG. 21 is a flowchart illustrating a method for adjusting an angle ofan arc chamber, in accordance with some embodiments. In step 510, an ionsource is received. The ion source includes a base plate, a first arcsupport plate, a second arc support plate, and an arc chamber supportedby the two arc support plates. Each arc support plate includes at leastone alignment screw which engages the base plate. An extractionelectrode is also present. The arc chamber includes an exit slit, andthe extraction electrode also includes a slit. The exit slit and theextraction electrode slit are arranged such that the ion beam exitingthe exit slit also passes through the extraction electrode slit.Different embodiments of ion sources having these features areillustrated in FIGS. 4-20.

In step 520, the ion source is activated to generate an initial ion beamcurrent value, which is measured beyond the extraction electrode slit.The ion beam current is reference numeral 150 in FIG. 1. In step 530,the measured value is compared to a reference to determine whether theion beam current is sufficient for use. In this regard, as seen in FIG.3A and FIG. 3B, insufficient alignment between the exit slit and theextraction electrode slit can reduce the ion beam current.

In step 540, the alignment screw on at least one arc support plate thatsupports the arc chamber is adjusted. The angle of the arc chamber isthus changed relative to the base plate to which the arc support plateis attached. This is illustrated in FIG. 13.

In step 550, the ion beam current is measured again. Desirably, thismeasured value is greater than the initial value measured in step 520.Steps 540, 550 can be repeated until the desired threshold value isachieved, or until the ion beam current is maximized. This is bestillustrated by comparing FIG. 3A with FIG. 3B, where the betteralignment of the arc chamber exit slit 128 with the extraction electrodeslit 148 in FIG. 3A results in a higher ion beam current 150. The methodthen ends at step 560.

The ability to adjust the altitude and angle of the arc chamber has theadvantage of increasing the beam quality of the ion source, as measuredby the mean or median ion beam current (SI unit=amperes). This is alsoknown as the straight beam performance from ion source to extraction. Insome embodiments, the beam quality is increased by at least 4%, or by atleast 5%, or by at least 6%, or by at least 7%, or by at least 8%, or byat least 9%, or by between about 4% to about 10%. In other embodiments,the axis offset can be decreased from +/−1.0 mm to +/−0.2 mm in the x-zplane or the y-z plane (where the base plate is in the x-y plane), orput another way to 20% of the original axis offset compared to astructure where the arm of the arc support plate does not have thethrough-hole and screw that engages the upper surface of the base plate.The increase in beam quality also provides an advantage of improvedproductivity, as the irradiated substrate (e.g. a silicon wafer) can beirradiated for a shorter time period to achieve the same dose, whichincreases throughput.

Some embodiments of the present disclosure thus describe an ion sourcefor an ion implanter. The ion source includes an arc chamber, which issupported by an arc support plate. The arc support plate comprises afront face and at least one arm extending beyond the front face. Infurther embodiments, the arm contains a plurality of through-holes. Inmore particular embodiments, the arc support plate has two arms.

Other embodiments of the present disclosure describe an assembly forsupporting an arc chamber, such as that used in an ion source. Theassembly comprises a first arc support plate, a base plate, a firstscrew, and a second screw. The arc support plate comprises at least onearm, the at least one arm containing at least a smooth through-hole. Thebase plate comprises an upper surface and a bore extending into theupper surface. The first screw passes through the smooth through-holeand into the bore of the base plate. The second (or alignment) screw canadjust an angle between the first arc support plate and the base plate.In some embodiments, the arm of the first arc support plate alsocontains a threaded through-hole, and the second screw passes throughthe threaded through-hole, with the tip of the second screw engaging theupper surface of the base plate. In other embodiments, the based platecontains a threaded through-hole, and the second screw passes throughthe threaded through-hole, with the tip of the second screw engaging alower surface of an arm of the first arc support plate. The assembly mayfurther include a second arc support plate, and an arc chamber supportedon opposite sides by the first arc support plate and the second arcsupport plate.

Other embodiments of the present disclosure relate to methods foradjusting an angle or an altitude of an arc chamber, by adjusting analignment screw on at least one arc support plate that supports the arcchamber. This causes the angle or the altitude of the arc chamber tochange relative to the base plate to which the arc support plate isattached.

The embodiments of the present disclosure are further illustrated in thefollowing non-limiting working example, it being understood that theexample is intended to be illustrative only and that the disclosure isnot intended to be limited to the materials, conditions, processparameters and the like recited herein.

EXAMPLE

The beam quality of an ion source using arc support plates asillustrated in FIGS. 4-11 was compared to an ion source that did not usearc support plates having arms which extended beyond the front face andprovided a screw which could be used to adjust the altitude and angle ofthe arc chamber. Two tests were performed, along with two comparativetests. The results are provided in the table below:

CIH109- CIH109- DIH104- DIH104- Comparative Example Comparative ExampleMean (μA) 6724.6 7181.1 6464.4 7048.9 Std Dev (μA) 484.7 204.2 382.4275.1 Median (μA) 6859 7184.1 6415.4 7045.2 5% (μA) 6124.9 6762.7 6025.96552.9 95% (μA) 7498.8 7568 7166.3 7474.8 % increase (mean) 6.8 9.0 %increase (median) 4.7 9.8

Both the mean and median values for the ion beam current weresignificantly higher for the two Examples than the two ComparativeExamples. The standard deviation was also lower, i.e. the ion beamcurrent fluctuated less even at the high currents.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An ion source for an ion implanter, comprising:an arc chamber supported by an arc support plate; wherein the arcsupport plate comprises a front face and at least one arm, the at leastone arm extending beyond the front face.
 2. The ion source of claim 1,wherein the arc support plate has two arms located on opposite sides ofthe arc support plate, the front face being located between the twoarms.
 3. The ion source of claim 1, wherein the at least one armcontains a plurality of through-holes.
 4. The ion source of claim 3,wherein at least one through-hole in the plurality of through-holes islocated in the at least one arm beyond the front face.
 5. The ion sourceof claim 3, wherein the plurality of through-holes includes a threadedthrough-hole and a smooth through-hole.
 6. The ion source of claim 3,wherein the plurality of through-holes includes one threadedthrough-hole and two smooth through-holes.
 7. The ion source of claim 1,further comprising a main portion having the front face, wherein themain portion includes an upper end above the at least one arm and alower end below the at least one arm.
 8. The ion source of claim 7,wherein the main portion further comprises two shoulders, such that alength of the upper end is shorter than a length of the lower end. 9.The ion source of claim 8, further comprising a leg extending downwardsfrom the lower end of the main portion, wherein the leg is offset to oneside.
 10. An assembly for supporting an arc chamber, comprising: a firstarc support plate, a base plate, a first screw, and a second screw;wherein the first arc support plate comprises at least one arm, the atleast one arm extending beyond the front face and containing a smooththrough-hole; wherein the base plate comprises a bore extending into anupper surface; wherein the first screw passes through the smooththrough-hole and into the bore of the base plate; and wherein the secondscrew can adjust an angle between the first arc support plate and thebase plate.
 11. The assembly of claim 10, wherein the at least one armof the first arc support plate also contains a threaded through-hole;and wherein the second screw passes through the threaded through-holeand engages an upper surface of the base plate.
 12. The assembly ofclaim 11, wherein the threaded through-hole is located in the at leastone arm beyond the front face of the first arc support plate.
 13. Theassembly of claim 10, wherein the base plate also contains a threadedthrough-hole; and wherein the second screw passes through the threadedthrough-hole and engages a lower surface of the at least one arm of thefirst arc support plate.
 14. The assembly of claim 10, wherein the firstscrew and the second screw are of different lengths, and optionallywherein the first screw and the second screw differ in length by atleast 0.5 mm.
 15. The assembly of claim 10, wherein the first arcsupport plate has two arms located on opposite sides of the first arcsupport plate and extending forward beyond a front face of the first arcsupport plate, with a front face of the first arc support plate beinglocated between the two arms.
 16. The assembly of claim 10, furthercomprising: a second arc support plate; and an arc chamber supported onopposite sides by the first arc support plate and the second arc supportplate.
 17. The assembly of claim 17, wherein the second arc supportplate has a different shape from the first arc support plate.
 18. Amethod of adjusting an angle or an altitude of an arc chamber,comprising: adjusting an alignment screw so as to change an angle or analtitude of at least one arc support plate that supports the arcchamber, relative to a base plate to which the arc support plate isattached.
 19. The method of claim 18, wherein the arc chamber issupported by two arc support plates that engage the base plate.
 20. Themethod of claim 18, wherein the alignment screw passes through an arm ofthe at least one support plate and pushes against an upper surface ofthe base plate; or wherein the alignment screw passes through the baseplate and pushes against a lower surface of an arm of the at least onesupport plate.